Justice reform is quickly becoming the hottest bipartisan cause—so much so that President Obama actually mustered up praise for both Rand Paul and the Koch brothers on the issue. But there’s one popular Republican who is decidedly against the whole movement: Scott Walker.

It’s a point that’s been made time and again—National Review has called him the “big exception to this trend,” while Reason dubbed him “Not the Candidate for Conservative Criminal Justice Reform.”

An array of Republican 2016 candidates—including Rand Paul, Rick Perry, and Ted Cruz—are all advocating for reforming federal sentencing and keeping low-level offenders out of prison. Even Marco Rubio, who still takes a fairly tough-on-crime stance, has conceded that the American legal system is “over-criminalized and over-federalized.”

Meanwhile, Walker has steadfastly opposed reform efforts. BuzzFeed’s recent delve into his history on the issue suggests that he may have stopped talking about crime as much as he once did—but that he’s still just as committed to his old positions.

In the past, he’s sponsored bills to increase mandatory minimum sentences and opposed attempts to reform his state’s parole system. Last month, he declared that “People being incarcerated for relatively low offenses is not a significant issue in the state of Wisconsin." 

This makes him out of step not only with the GOP field, but also with some major potential backers: the Koch brothers.

The Kochs have made no secret of their fondness for Walker, joking to reporters that while they’ll stay neutral on the field for now, “When the primaries are over and Scott Walker gets the nomination, well…then we will support.”

But the brothers have also been some of the strongest proponents for criminal justice reform over the years, pronouncing it one of their core issues in 2015. As Yahoo News observes, this could all put Walker in an awkward position come 2016.